High intensity lights are needed for applications such as helideck beacons. In the past such beacons have been conventional filament lights. However, filament lights are energy and maintenance intensive. Recently, beacons have used light emitting diodes (“LED”) in conjunction with optical elements to channel the emitted light. LEDs create unique requirements in order to be commercially viable in terms of size, weight, price, and cost of ownership, compared to conventional filament lights, but are more energy efficient and require less maintenance.
The light emission of helideck perimeter lights is controlled by international aeronautical regulations, namely the Civil Aviation Authority's “CAP 437” standard. The intensity requirements over 360° of the azimuth for helideck perimeter beacon lights are given in terms of elevation angles from the horizon (0° being at the horizon and 90° being the straight vertical): a 60 candela maximum for 0° to 90°, a 3 candela minimum for 20° to 90°, a 15 candela minimum for 10° to 20° and a 30 candela minimum for 0° to 10°. In current LED based designs, LED signals/beacons requiring an omni-directional light profile which primarily emit light in a substantially horizontal plane have used multiple optical elements to translate the light emitted from the LED (that is a near-Lambertian source) into the required emission pattern. Such beacons are required to have a battery back-up. However, the multiple optical elements result in loss of light emitted from the LED and therefore result in greater than necessary battery drain if in a back-up mode.
Current helideck light designs using LEDs suffer from complex manufacturing requirements due to the multiple optical elements required. Further, these light designs are not efficient, because light passing through or reflecting off of multiple media results in loss of light and therefore inefficient use of energy. A superior helideck light design would exhibit a low cost of manufacture and high energy efficiency to satisfy the additional requirement for installations to have a battery back-up.